Electrical contact for equipment used in the electrolytical production of metals,particularly copper

ABSTRACT

AN ELECTRICAL CONTACT BETWEEN MOVING AND STATIONARY CONDUCTING ELEMENTS, IN PARTICULAR FOR EQUIPMENT USED IN THE ELECTROLYTICAL PRODUCTION OF METALS, SUCH AS COPPER IN FORM OF PLATES, WHICH ELIMINATES THE WEARING OF THE CONTACT POINTS, THE VOLTAGE DROPS, THE OVERHEATING OF THE MOVABLE CONTACT AND OTHER INCONVENIENCES. THIS CONTACT ESSENTIALLY COMPRISES A MERCURY BATH CONTAINED WITHIN A NUMBER OF BEADS OF FLEXIBLE AND ELECTRO-INSULATING MATERIAL, AND THE INSIDE FACE OF A METALLIC BELT ROTATABLY MOUNTED AROUND PULLEYS. IN THIS BATH IS IMMERSED A CONDUCTING BAR SPACED FROM SAID BELT BY MEANS OF PAWLS IN ANTI-FRICTION INSULATING MATERIAL IN ORDER TO PREVENT THE DIRECT CONTACT BETWEEN THE BAR AND THE ROTATING BELT.

3,799,861 LYTICAL TICULARLY COPPER Mamh 1974 B. Dl PIETRO ELECTRICALCONTACT FOR EQUIPMENT USED IN THE ELECTRO PRODUCTION OF METALS PAR FiledJuly 14, 72

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United States Patent O 3,799,861 ELECTRICAL CONTACT FOR EQUIPMENT USEDIN THE ELECTROLYTICAL PRODUCTION OF METALS, PARTICULARLY COPPER Bruno DiPietro, Milan, Italy, assignor to Raptes Researches Applications andTrade Establishment, Triesen, Liechtenstein Filed July 14, 1972, Ser.No. 271,985 Claims priority, application Italy, July 22, 1971, 7,592/71Int. Cl. B01k 3/00 US. Cl. 204279 9 Claims ABSTRACT OF THE DISCLOSURE Anelectrical contact between moving and stationary conducting elements, inparticular for equipment used in the electrolytical production ofmetals, such as copper in form of plates, which eliminates the wearingof the contact points, the voltage drops, the overheating of the movablecontact and other inconveniences. This contact essentially comprises amercury bath contained within a number of beads of flexible andelectro-insulating material, and the inside face of a metallic beltrotatably mounted around pulleys. In this bath is immersed a conductingbar spaced from said belt by means of pawls in anti-friction insulatingmaterial in order to prevent the direct contact between the bar and therotating belt.

BACKGROUND OF THE INVENTION The present invention relates to anelectrical contact for equipment used in the manufacture of metal tapes,such as copper, through the electrolytic process.

It is known in the art the use of machines for the manufacture ofelectrolytic copper in plate or tape form, consisting essentially ofconveyor belts, moved in various ways, said belts acting as the cathodein the electrolytic process, running in a bath contained in a tank, onthe bottom of which there is placed an anodic element from which themetallic ions are liberated and deposited on the surface of the conveyorbelt serving as the cathode.

Such machines, however, present some problems concerning the electricalcontact placed on the belt. In fact, in view of the movement of saidbelt, it is necessary to create an electrical contact between movingparts and fixed parts, with all the problems that such an arrangementinvolves. Various inconveniences have in fact been found in practice,such as: wearing of the contact points, voltage drops, spottyoverheating of the carrying belt, which cause deformation of same,shortening its life. If the electrical contact produces overheating,local annealings are the consequence, and these shorten the life of thebelt itself enormously.

Moreover, the sparkings and burnings produced by the creeping electricalcontacts alter the composition of the alloy, in that they cause aprecipitation of carbides in the zone subjected to the overheating. Thisprecipitation of carbides exposes the stainless steel to rapid chemicalcorrosion, which leads to the perforation of the belt in a short time,whereas in the meantime the electrolytically deposited material toremain attached to said zone, causing its own perforation and breakageat the instant the cathode support is removed.

SUMMARY OF THE INVENTION It is a main object of the present invention toprovide a type of electrical contact capable of completely eliminatingthe wearing of the contact points in an apparatus of the above-mentionedtype.

Another object of the present invention is that of 3,799,861 PatentedMar. 26, 1974 eliminating the voltage drops in the contact zone betweenthe moving elements and the fixed elements.

Still another important object of the present invention is that ofavoiding overheating of the carrying belt. A- -last butnot least objectis that of obtaining a de crease in the current from the center of thebelt toward the edges, in such a manner that uniform thicknesses ofmetal plate are obtained as desired.

These and further objects are obtained by means of an electrical contactfor equipment used in the manufacture of electrolytic metals in plateform, particularly copper, in accordance with the invention, suitablefor bringing'into electrical contact movable elements and fixedelements, and characterized by the fact that it comprises metallicelements, a mercury bath, means for spacing said metallic elements, aswell as means for containing said bath.

BRIEF DESCRIPTION OF THE DRAWINGS The invention will be fully understoodfrom the following detailed description of a preferred but not exclusiveembodiment of an electrical contact illustrated by way of a non-limitingexample only, with reference to the annexed drawing in which:

FIG. 1 is a cross-sectional 'view of a device for obtaining electrolyticmetal in plate form, provided with an electrical contact according tothe invention;

FIG. 2 is a cross-section along the line 11-11 of FIG. 1.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to thementioned figures, the electrical contact according to the invention,indicated overall with 1, is arranged within a metal belt 2 of steel,wound around pulleys 3, keyed onto shafts 4 which are rotatably mountedon fixed supports 5. The lateral edges of said belt 2 are provided withrims of flexible insulating material 6. These rims are acid-resistantand are adapted to prevent the spreading of the electrolytic liquid 7onto the internal face of said belt 2. Said electrolytic liquid 7 iscontained in a tank 8.

The electrical contact 1 according to the invention, consists of aconducting bar 9, immersed in a bath 10 of mercury, which is containedin a space confined by beads 11, of flexible and insulating material,which beads are in contact with the inside part of said belt 2. Theconducting bar 9 can be for example of copper plated with nickel orother metal, that mercury does not attack.

Between said conducting bar 9 and said belt 2 there are placed pawls'12' in anti-friction insulating material, of such nature (for examplein plastic type Teflon) which is not attacked by mercury, said pawlshaving the function of spacers for said metallic conducting bar 9 andsaid belt 2 to prevent the possibility of local overheating and burning,in the event of direct contact. Said beads 11 are extended over theentire internal perimeter of said belt 2, but for obvious reasons ofgravity, the mercury bath 10 is limited to the bottom zone of the spacedefined by said beads 11 and the inside face of belt 2. On the bottom oftank '8 there are placed pieces of metal 13, for example copper, whichare to be deposited electrolytically, in sheet or tape form 131: on theface of belt 2, which is immersed in bath 7. In the electrochemicalprocess, the metallic bar 9 serves as cathode, while the function ofinsoluble anode is assumed by a conductor layer of lead 14, on which thepieces of copper 13 are placed. Said bar 9 and said conductor layer 14are connected, through conductors 15, to a generator of electromotiveforce, not shown in the figure.

The operation of the electrical contact according to the invention issimple. The mercury bath closes the 3 circuit comprising saidelectromotive-force generator, said conductors 15, bar 9, belt 2,electrolytic bath 7, the pieces of metal 13, and the lead conductorlayer 14. During the operation of the machine, the mercury 10, thanks toits high specific gravity as well as to its poor adhesive forces, doesnot follow the movement of the.

belt '2 but always remains in the lower position of the space defined bythe beads 11 and the inside face of belt 2. In this manner theelectrical contact is always assured, since bar 9 permanently remainsimmersed in mercury bath 10.

It has been found in practice how the electrical contact according tothe invention eliminates 'the inconveniences encountered in the knowntypes of electrical contacts of thecreeping type and similar betweenfixed and moving members. In fact, employing the electrical contact ofthe invention, all the phenomena of wear and tear of the contacts,voltage drops, overheating and burning of the steel support belt and thelike, shown by the usual contacts do not appear. Further very importantfact, it has been found that the electrical contact employing mercury,according to the invention, assures a distribution of electricalpotential on the entire surface of belt 2 with a high degree ofuniformity. It has been found that it is preferable for the metalliccarrying bells to be constructed of rolled steel (not annealed) with ahigh ultimate stress. This is for the purpose of having a high degree ofelasticity, so that when the belt turns on the pulleys it will notretain the curved form of the pulley but will immediately straighten outupon leaving same.

If, on other hand, annealed belts were used having little elasticity,the metal winding around the pulley would have a tendency to retain thecurved form; it would then be straightened out as a result of the pullexerted by the tension of the belt on the pulleys. In this case,however, the belt would be subjected to a succession of transversebends, which would be produced at every revolution, locally causinggreater and greater workhardenings at every bend, inevitably leading tobreakage.

It is therefore necessary that the carrying belt shows thosecharacteristics of hardness and elasticity that are found only in rolledsteel in the non-annealed state. This new type of contact thus permitsto maintain unchanged these characteristics, which on the contrary, incase of other types of contact would be modified owing to the localoverheatings causing the annealing of the steel.

Thanks to the new contact according to the invention, it is possible tooperate with high currents, no longer being subjected to the limitationsimposed by the creeping type of contact, operation of which gets worseas the current increases.

I The great advantage of this invention is that the productivity of theapparatus is increased,-the production being proportional to thecurrent. By using the contact according to the present invention thelimitations of current intensity, and thus of production, for thedevices using creeping contacts of the conventional type, is overcome.

The invention thus conceived is susceptible to numerous changes andvariations, falling all within the scope of the present invention asdefined by the appended claims.

It is obvious that the materials used, as Well as the dimensions, can beany that are desired in accordance with the requirements and,furthermore, all the described parts can be replaced with others thatare technically equivalent. Thus for example the mercury can besubstituted by a conducting substance of suitable analogouscharacteristics.

What I claim is: v

1. For use in apparatus for the electrolytical production of metallicplates, an electrical contact assembly comprising a stationaryelectrically conductive bar, an electrically conductive conveyor beltadapted to move relative to said bar, the belt being adapted to receiveon a first surface thereof the electrolytic metal of which the metallicplate is formed, said bar being spaced from said belt, means forcontaining a mercury bath, said mercury bath in continuous contact witha second surface of said belt, at least a portion of said bar beingimmersed in said bath, said bar being adapted to be connected to anelectromotive force generator.

2. An electrical contact assembly as defined in claim 1 wherein saidbelt is made of rolled, non-annealed steel. 3. An electrical contactassembly as defined in claim 1 wherein said bar is plated with a metalwhich mercury i does not attack.

4. An electrical contact according to claim 3, wherein said metal forplating said bar is nickel.

5. An electrical contact assembly as defined in claim 1 including meansfor spacing said bar from said belt.

6. An electrical contact assembly as defined in claim 5 wherein thespacing means comprises a plurality of pawls of anti-friction andelectrical insulating material.

7. An electrical contact according to claim 1, wherein said means forcontaining said mercury bath comprises beads of flexible andelectro-insulating material.

8. An electrical contact according to claim 7, wherein said beads offlexible and insulating material are in contact with all of said secondsurface of said belt wound around driving pulleys.

9. An electrical contact according to claim 8, wherein said mercury isconfined in the space created by said beads of flexible and insulatingmaterial and by said second surface of said belt, in such a quantity asto fill only the part of said space that is adjacent to said secondsurface of the section of said belt, which is immersed in anelectrolytic bath.

References Cited UNITED STATES PATENTS 2,882,214 4/1959 Summers et al.204-279 FOREIGN PATENTS 251,901 3/1963 Austria 204-208 JOHN H. MACK,Primary Examiner w. I. SOLOMON, Assistant Examiner U.S. Cl. X.R.

